This invention relates to a hydraulic capsule pipelining system, and more particularly to an injection system for injecting capsules into a hydraulic capsule pipelining system.
Reference may be made to such U.S. Pat. Nos. as 3,325,222, 3,328,089, 3,333,901, 3,339,984, 3,556,604 and 3,633,976 disclosing hydraulic capsule pipelining (HCP) systems in which the flow of a carrier liquid through a pipeline is used to propel capsules, and in particular cargo-carrying containers, through the pipeline.
A problem with hydraulic capsule pipelining systems, which has hindered greater commercial use of such systems as a mode of cargo transport, has been the lack of a satisfactory capsule injection system for injecting the capsules, which are large and relatively heavy when loaded with cargo, into the pipeline. Among various capsule injection systems that have been proposed are injection systems of the "lock" type having a reservoir of carrier liquid, and a pipeline downstream from the reservoir having a series of valves, suction means, and a pump operable for drawing carrier liquid and the capsules into the pipeline from the reservoir and for pumping the carrier liquid through the pipeline to propel the capsules. The structure of this capsule injection system is relatively complex and its operation involves a complicated sequence of valve openings and closings and pumping operations which can generate destructive pressure surges in the pipeline (i.e., water hammer).
Another type of capsule injection system is the "multi-barrel revolver" type comprising a cylinder received in a space between axially aligned sections of the pipeline, the pipeline thus extending upstream and downstream of the cylinder. The cylinder has a series of chambers or bores arranged in a circular series around the longitudinal axis of the cylinder, each chamber being adapted to receive a capsule from a capsule feeding means. The cylinder is rotatably mounted so that upon rotation of the cylinder each chamber may be brought into alignment with the pipeline for enabling the flow of carrier liquid from the upstream pipeline section through the chamber to propel the capsule along the pipeline. One problem with this capsule injection system is the leakage of carrier liquid at the juncture between the cylinder and the pipeline. Another is the difficulty of accurately controlling the angular position of the cylinder which is relatively large and bulky.
Other proposed capsule injection systems include the "rotary-vane pump" system having a large pump rotor adapted to receive capsules between adjacent pump vanes and a housing opening into the pipeline, and the "multi-tube launcher" system having a reservoir, and series of open-ended launching tubes on a conveyor belt in the reservoir, the tubes being movable past an inlet to the pipeline. A source of carrier liquid under pressure is provided for directing carrier liquid at the upstream end of the capsules to move the capsules in the launcher tubes along the tubes into the pipeline. Both of these systems, however, are relatively large and expensive.